The construction of buildings, walls, pools and like structures is greatly facilitated by being able to inject or apply pre-mixed cement, or similar flowable materials of mud-like viscosity, under pressure at the construction site. Pumps employing various types of impellers, augers and similar mechanisms have been used to accomplish this function. Reciprocating piston concrete pump designs are disclosed in the applicant's U.S. Pat. No. 4,174,928, and in the patent to Schwing, U.S. Pat. No. 3,146,721.
For pumping cement, a pump which requires close tolerance fits between parts, or which depends on complex interconnections between pump components and parts of the flow material distribution system for proper operation is difficult to use and maintain. Cement and other such water mixture materials tend to clog any device with which they come in contact, and if permitted to set can render the pump inoperative. It is desirable, therefore, that a cement pump be of simple design and construction with few moving parts, and without intricate control features. Also, since different jobs require the use of pre-mixes having different water content, and therefore having different viscosity and drying characteristics, it is desirable to have a pump capable of readily accommodating different flow materials. In addition, such a pump should be compact and transportable, yet be of sturdy construction, reliable in operation, and easily maintained. Applicant's cement pump meets theses and other requirements.